The following references are believed to represent the state of the art:    an article entitled “Rate-Adaptable Optics for Next Generation Long-Haul Transport Networks”, by Xiang Zhou, Lynn E. Nelson, and Peter Magill, in IEEE Communications Magazine, March 2013, pages 41-49;    an article entitled “Extending Software Defined Network Principles to Include Optical Transport”, by Steven Gringeri, Nabil Bitar, and Tiejun J. Xia, in IEEE Communications Magazine, March 2013, pages 32-40;    an article entitled “Spectrum-Efficient and Agile CO-OFDM Optical Transport Networks: Architecture, Design, and Operation”, by Gangxiang Shen and Moshe Zukerman, in IEEE Communications Magazine, May 2012, pages 82-89;    an article entitled “Spectrum-Efficient and Scalable Elastic Optical Path Network: Architecture, Benefits, and Enabling Technologies”, by Masahiko Jinno, Hidehiko Takara, Bartlomiej Kozicki, Yukio Tsukishima, Yoshiaki Sone, and Shinji Matsuoka, in IEEE Communications Magazine, November 2009, pages 66-73;    an article entitled “Advanced Optical Modulation and Multiplexing Technologies for High-Capacity OTN Based on 100 Gb/s Channel and Beyond”, by Yutaka Miyamoto and Senichi Suzuki, in IEEE Communications Magazine, March 2010, pages S65-S72;    an article entitled “Higher-Order Modulation for Client Optics”, by Chris Cole, Ilya Lyubomirsky, Ali Ghiasi, and Vivek Telang, in IEEE Communications Magazine, March 2013, pages 50-57;    an article entitled “IETF Work on Protection and Restoration for Optical Networks”, by David W. Griffith in Optical Networks Magazine, July/August 2003, pages 101-106;    an article entitled “Optical Transceivers for 100 Gigabit Ethernet and its Transport”, by Jon Anderson and Matthew Traverso, in IEEE Communications Magazine, March 2010, pages S35-S40;    an article entitled “Ultra-High-Capacity DWDM Transmission System for 100G and Beyond”, by Jianjun Yu and Xiang Zhou, in IEEE Communications Magazine, March 2010, pages S56-S64;    an article entitled “Next-Generation 100 Gb/s Undersea Optical Communications”, by Yasuhiro Aoki, Yoshihisa Inada, Takaaki Ogata, Lei Xu, Shaoliang Zhang, Fatih Yaman, and Eduardo Mateo, in IEEE Communications Magazine, February 2012, pages S50-S57;    an Implementation Agreement IA # OIF-PMQ-TX-01.0 entitled “Implementation Agreement for Integrated Polarization Multiplexed Quadrature Modulated Transmitters”, technical editor Martin Bouda, of the Physical and Link Layer (PLL) Working Group of the Optical Internetworking Forum (OIF), dated Mar. 12, 2010, available on the World Wide Web at www.oiforum.com/public/impagreements.html; and    an Implementation Agreement IA # OIF-DPC-RX-01.1 entitled “Implementation Agreement for Integrated Dual Polarization Intradyne Coherent Receivers”, maintenance editor Anthony J. Ticknor, of the Physical and Link Layer (PLL) Working Group of the Optical Internetworking Forum (OIF), dated Sep. 20, 2011 available on the World Wide Web at www.oiforum.com/public/impagreements.html.